Motion guide device and actuator

ABSTRACT

A track member or a movable member constituting a motion guide device includes a rolling part formed of a metal material contacting with a plurality of rolling bodies and forming a rolling body rolling surface a, a mounting part formed of a metal material having a mounting hole for mounting an external member, and a track body or a movable body formed of FRP jointed with the rolling part and the mounting part and forming the track member or the movable member, and the mounting part and the track body or the movable body have joint holes, opened in a direction orthogonal to a lamination direction of FRP reinforced fiber sheets S forming the track body or the movable body at a time of the joint, and can be jointed using jointing means. An external member can be securely mounted to the motion guide device formed of FRP.

TECHNICAL FIELD

The present invention relates to a motion guide device and an actuatorincorporating the motion guide device.

BACKGROUND ART

Conventionally, in motion guide devices such as a linear guide, a linearguide device, a ball spline device, and a ball screw device, sincemembers constituting such a device move with repeated rolling andsliding motions, a high hardness metal material such as high-carbonchromium bearing steel, stainless steel, or case-hardening steel hasbeen used for the structural members.

However, due to the requirement for expanding the application range ofmotion guide devices in recent years, lightweight devices areparticularly required, and ideas for reducing weight have been proposedto respond to this requirement. For example, Patent Literature 1 of thisapplicant discloses a motion guide device using fiber reinforcedplastics (FRP) that is a material having strength and rigidityequivalent to those of a metal material such as steel, and also achievesweight reduction. This FRP reinforces plastics by using fiber and resin,can significantly improve strength, and is a material used in variousfields such as a space and aviation industry, a motorcycle industry, anautomobile industry, a railway industry, and a construction industry,and a medical field. However, conventional FRP has been inferior inabrasion resistance as compared with metal materials. For this reason,the applicant has developed a technique for using FRP to motion guidedevices, and proposed a motion guide device achieving weight reductionthat was not able to be achieved by the technology using only metalmaterials in Patent Literature 1.

CITATION LIST Patent Literature

Patent Literature 1: JP 4813373 B

DISCLOSURE OF THE INVENTION Problems to be Solved By the Invention

Incidentally, when an external member is mounted on a constitutingmember of an FRP motion guide device, a screw hole has been formed byinserting a helisert in the FRP lamination surface, and the externalmember has been installed using the screw hole. However, the helisertembedded by being inserted in the FRP lamination surface has adifficulty in ensuring the strength because the helisert itself rotateswhen tightened with torque equal to or greater than a control value offastening torque. In other words, a motion guide device formed of FRPneeds to be provided with means for securely mounting an externalmember.

The present invention has been made in view of the above problem in theconventional technique, and is to provide a motion guide device formedof FRP with means for securely mounting an external member.

Means For Solving the Problems

A motion guide device according to the present invention is a motionguide device including a track member, and a movable member mounted onthe track member so as to freely move via a plurality of rolling bodies,in which the track member or the movable member includes a rolling partformed of a metal material contacting with the plurality of rollingbodies and forming a rolling body rolling surface, a mounting partformed of a metal material having a mounting hole for mounting anexternal member, and a track body or a movable body formed of FRPjointed with the rolling part and the mounting part and forming thetrack member or the movable member, and the mounting part and the trackbody or the movable body each have a joint hole opened in a directionorthogonal to a lamination direction of FRP reinforced fiber sheetsforming the track body or the movable body at a time of the joint, andcan be jointed using jointing means placed in the joint holes.

Another motion guide device according to the present invention is amotion guide device including a track member, and a movable membermounted on the track member so as to freely move via a plurality ofrolling bodies, in which the track member or the movable member includesa rolling part formed of a metal material contacting with the pluralityof rolling bodies and forming a rolling body rolling surface, a mountingpart formed of a metal material having a mounting hole for mounting anexternal member, and a track body or a movable body formed of FRPjointed with the rolling part and the mounting part and forming thetrack member or the movable member, and the mounting part and the trackbody or the movable body each have a joint surface extending in adirection parallel to a lamination direction of FRP reinforced fibersheets forming the track body or the movable body at a time of thejoint, and can be jointed using jointing means applied to the jointsurfaces.

In the present invention, it is possible to constitute an actuator byincorporating either of the above motion guide devices.

Effects of the Invention

According to the present invention, it is possible to provide a motionguide device formed of FRP with means for securely mounting an externalmember. Furthermore, according to the present invention, it is possibleto provide an actuator incorporating the motion guide device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cutaway view for explaining a schematicstructure of a motion guide device according to a first embodiment.

FIG. 2 is a vertical sectional view of the motion guide device accordingto the first embodiment.

FIG. 3 is a vertical sectional view for explaining a structure of atrack rail according to the first embodiment.

FIG. 4 is a vertical sectional view for explaining a structural exampleof a movable member to which an embodiment of the present invention isapplied.

FIG. 5 is an appearance perspective view showing an example of a usingstate of the motion guide device according to the first embodiment.

FIG. 6 is a schematic view for explaining characteristics of FRP that isa constituting member of the motion guide device according to the firstembodiment.

FIG. 7 is a view for explaining a main portion of the motion guidedevice according to the first embodiment.

FIG. 8 is a view showing a case in which the first embodiment is appliedto a movable member.

FIG. 9 is a view showing an example of various possible modifications ofthe motion guide device according to the first embodiment.

FIG. 10 is a view showing another example of various possiblemodifications of the motion guide device according to the firstembodiment.

FIG. 11 is a partial perspective view showing a main portion of a motionguide device according to a second embodiment; FIG. 11(a) shows that amounting part is not being mounted to a stepped machining portion, andFIG. 11(b) shows that the mounting part is being mounted to the steppedmachining portion.

FIG. 12 is a view for explaining a motion guide device according to athird embodiment; FIG. 12(a) is a perspective view showing the overallstructure of the motion guide device, FIG. 12(b) is a vertical sectionalview of a main portion showing the vicinity of a bolt mounting hole, andFIG. 12(c) is a schematic view for explaining the characteristics of FRPthat is a constituting member of a track rail.

FIG. 13 is a view showing a specific implementation example of the thirdembodiment.

FIG. 14 is a partial vertical sectional view showing an example animprovement of a metal collar according to the third embodiment.

FIG. 15 is a view for explaining a track rail used in a motion guidedevice according to a fourth embodiment; FIG. 15(a) is an explodedperspective view showing the bottom surface side of the track railbefore assembly, FIG. 15(b) is a perspective view showing the bottomsurface side of the track rail after assembly, and FIG. 15(c) is aperspective view showing the upper surface side of the track rail afterassembly.

FIG. 16 is a view showing a case in which a bolt as fastening means isplaced to a state view showing a section A-A in FIG. 15(c).

FIG. 17 is a view exemplifying a case in which a motion guide device inaccordance with an embodiment of the present invention is configured asa ball screw device.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments for carrying out the presentinvention will be described with reference to the drawings. Note that,the following embodiments do not limit the invention according to eachclaim and all combinations of features described in the embodiments arenot necessarily required for the solution means of the invention.

A “motion guide device” in this specification includes devices thatmoves with any rolling and sliding motions such as general rollingbearings used for machine tools, non-lubricant bearings used in vacuum,linear guides, linear guide devices, ball spline devices, ball screwdevices, and roller rings.

First Embodiment

FIGS. 1 and 2 are views showing an example of a motion guide deviceaccording to a first embodiment. Particularly, FIG. 1 is a perspectivecutaway view for explaining a schematic structure of the motion guidedevice according to the first embodiment, and FIG. 2 is a verticalsectional view of the motion guide device according to the firstembodiment.

A motion guide device 10 is the motion guide device 10 having anintegral structure in which a linear motion guide and a ball screw arecombined. By connecting the ball screw to a motor (not illustrated), themotion guide device 10 functions as an actuator according to the presentinvention.

As a main structure, the motion guide device 10 according to the firstembodiment includes a track rail 11 as a track member and a movablemember 13 mounted on the track rail 11 so as to freely move via aplurality of balls 12 as rolling bodies. In addition, an opening 13 b inwhich a spiral screw groove is formed is provided in the center portionof the movable member 13. The opening 13 b is provided with a screwshaft 14 which is inserted through the opening 13 b and is mounted so asto freely rotate and move via the balls 12.

The track rail 11 is an elongated member having a substantially U-shapedvertical section, and two rolling-body rolling grooves 11 a capable ofaccommodating the balls 12 are formed on each inner side surface of thetrack rail 11 over the entire length of the track rail 11. A pluralityof bolt mounting holes 11 b are formed on the bottom surface side of thesubstantially U-shaped vertical section of the track rail 11 atappropriate intervals in the longitudinal direction of the track rail11. The track rail 11 is to be fixed to a predetermined mountingsurface, for example, the upper surface of the bed of a machine toolwith bolts (not illustrated) to be screwed into the bolt mounting holes11 b. Although the illustrated track rail 11 is linear, a curved railmay be used.

The movable member 13 is configured as a block having a structure inwhich a hole is bored in a high-strength metal material such as steel.The movable member 13 is provided with four loaded-rolling-body rollinggrooves 13 a each opposed to the four rolling-body rolling grooves 11 aof the track rail 11. By the combinations of the rolling-body rollinggrooves 11 a and the loaded-rolling-body rolling grooves 13 a, fourloaded-rolling-body rolling passages 15 are formed between the trackrail 11 and the movable member 13. In addition, a plurality of femalescrews 13 d (three screws shown in FIG. 1, but actually four screws) isformed on an upper surface 13 c of the movable member 13. By using thesefemale screws 13 d, the movable member 13 is to be fixed to apredetermined mounting surface, for example, the saddle of a machinetool or the lower surface of a table. Note that, the movable member 13is not limited to the one formed of a metal material alone, but may havea structure including a synthetic resin molded body injection-moldedintegrally with a high-strength metal material such as steel.

In the movable member 13, four return passages 16 extending in parallelto the four loaded-rolling-body rolling passages 15 are formed. Themovable member 13 further has lids 18 on both end faces thereof. By ballguiding grooves (not illustrated), which are each recessed in an archshape, formed in the lids 18, direction change passages 17 (in FIG. 1,two direction change passage 17 only on one corner side are shown withthe lid 18 removed), which are formed so as to each protrude in an archshape between the loaded-rolling-body rolling passage 15 and the returnpassage 16, are formed.

The pair of lids 18 is securely fixed as members constituting the endportions of the movable member 13, and therebetween, the directionchange passage 17 connecting the loaded-rolling-body rolling passage 15and the return passage 16 is formed. The return passage 16 and thedirection change passage 17 constitute a non-loaded-rolling-body rollingpassage 19 of the balls 12, and the combination of thenon-loaded-rolling-body rolling passage 19 and the loaded-rolling-bodyrolling passage 15 constitutes an infinite circulation passage 20.

In addition, between the balls 12 of the motion guide device 10according to the first embodiment, spacer members 21 which are softerthan the balls 12 are placed. Regarding the spacer members 21 shown inFIG. 1, the belt-shaped spacer member 21 is employed as the one placedbetween the track rail 11 and the movable member 13, whereas the spacermembers 21 as retainers inserted one by one between the balls 12 areemployed as the ones placed between the movable member 13 and the screwshaft 14. However, the combinations of the types and the installationsof the spacer members 21 are not limited to those exemplified in FIG. 1,and spacer balls each having a diameter equal to or less than thediameter of the balls 12 as rolling bodies can be employed. The spacermembers 21 placed in this manner can prevent the balls 12 frominterfering and colliding with each other, falling off, and the like,achieve the alignment motion of the balls 12, and significantly improvethe wear resistance of the motion guide device 10 in combination withthe self-lubricating effect of the spacer members 21.

Here, a feature of the motion guide device 10 according to the firstembodiment is that, in the track rail 11 as the track member, thevicinity of the rolling body rolling surface (rolling-body rollinggroove 11 a) contacting with the balls 12 is formed of a metal material,and the other portion is formed of FRP. With this feature, the motionguide device 10 according to the first embodiment can maintain strengthand rigidity equal to or higher than those of a conventional motionguide device, and also achieve weight reduction.

The structure of the track rail 11 according to the first embodimentwill be described in more detail with reference to FIG. 3. FIG. 3 is avertical sectional view for explaining the structure of the track rail11 according to the first embodiment.

The track rail 11 according to the first embodiment is formed byjointing two members of a rolling part 30 formed of a metal material anda track body 31 formed of FRP. The rolling part 30 formed of a metalmaterial is required to have high strength, high rigidity, and furtherwear resistance. As the metal material used for the rolling part 30,high hardness metal such as high-carbon chromium bearing steel,stainless steel, or case-hardening steel can be used, and aluminumalloy, beryllium copper, titanium alloy or the like can be also used.

On the other hand, the track body 31 is formed of FRP, and this achievesthe weight reduction of the motion guide device 10 according to thefirst embodiment. The type of used FRP is preferably at least one ofcarbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics(GFRP), and kevlar fiber reinforced plastics (KFRP). In particular, CFRPhas excellent strength, and is a preferred material because it ispossible to impart strength to a desired shape by changing thelamination direction and the number of layers of carbon fiber, and tofurther reduce the weight.

In the motion guide device 10 according to the first embodiment shown inFIGS. 1, 2 and 3, the track rail 11 alone is formed of a metal materialand FRP, but the present invention is not limited to this embodiment,and is also applicable to the movable member 13 or the screw shaft 14 asshown in FIG. 4. That is, it is possible to form the vicinity of thefour loaded-rolling-body rolling grooves 13 a forming theloaded-rolling-body rolling passages 15 in cooperation with the fourrolling-body rolling grooves 11 a of the track rail 11 by a rolling part40 formed of a metal material, to form the vicinity of the four returnpassages 16 extending in parallel to the four loaded-rolling-bodyrolling passages 15 by a rolling part 41 formed of a metal material, toform the vicinity of the opening 13 b in which the screw shaft 14 isplaced via the balls 12 by a rolling part 42 formed of a metal material,or to form the outer peripheral portion of the screw shaft 14 contactingwith the balls 12 by a rolling part 44 formed of a metal material, andto form the other portion as a movable body 43 formed of FRP. By formingnot only the track rail 11 but also the movable member 13 or the screwshaft 14 by jointing a metal material and FRP in this manner, it ispossible to further reduce the weight.

In addition, as the method for jointing the rolling part 30 formed of ametal material and the track body 31 formed of FRP, the rolling parts40, 41, and 42 formed of a metal material and the movable body 43 formedof FRP, or the rolling part 44 formed of a metal material and the otherportion of the screw shaft 14 formed of FRP, any one of adhesive joint,press-fitted joint, and bolted joint, or a combination thereof can beadopted.

For example, in the case of the track rail 11 shown in FIG. 3, it ispreferable to perform adhesive joint with an adhesive. Alternatively, inthe case of the movable member 13 shown in FIG. 4, it is preferable toperform adhesive joint with an adhesive to the rolling part 40 formingthe vicinity of the loaded-rolling-body rolling grooves 13 a, and toperform press-fitted joint to the rolling parts 41 and 42 forming thevicinity of the return passages 16 and the vicinity of the opening 13 b.In the press-fitted joint, by knurling the outer peripheral surfaces ofthe rolling parts 41 and 42 or the inner peripheral surfaces of thereturn passages 16 and the opening 13 b, and performing press-fitting,it is possible to securely perform the joint. Furthermore, it ispossible to adopt bolted joint to increase joint strength, and it isalso possible to adopt a jointing method combining adhesion joint andbolted joint or press-fitted joint and bolted joint as a more securejointing method. However, in the case of bolted joint, it is necessaryto pay attention so that the head of the bolt or the like does notaffect the motion of the motion guide device 10. Regarding a memberhaving a shape like the screw shaft 14, an optimal jointing method isappropriately adopted according to the appearance shape, the material,and the like.

The basic structure of the motion guide device 10 according to the firstembodiment has been described above with reference to FIGS. 1 to 4.Next, an additional feature of the motion guide device 10 according tothe first embodiment will be described with reference to FIGS. 5 to 7.Here, FIG. 5 is an appearance perspective view showing an example of ausing state of the motion guide device 10 according to the firstembodiment, FIG. 6 is a schematic view for explaining characteristics ofFRP that is a constituting member of the motion guide device 10according to the first embodiment, and FIG. 7 is a view for explaining amain portion of the motion guide device 10 according to the firstembodiment.

In the motion guide device 10 according to the first embodimentdescribed above, end housings 51 and 52 are mounted on both end portionsin the longitudinal direction of the track rail 11 in some cases asshown in, for example, FIG. 5. The end housings 51 and 52 are membersused for supporting the screw shaft 14 which can freely rotate and move,for mounting an external power source, or as an adjustment margin for aconstituting member of the motion guide device 10 such as the screwshaft 14. Thus, the end housings 51 and 52 are members necessary to bemounted with higher accuracy than a predetermined value.

However, as described in the paragraphs of the background art, if theend housings 51 and 52 are mounted on both end portions of the FRP trackrail 11 in the longitudinal direction simply by boring a screw hole orinserting a helisert, there is a difficulty in ensuring the strength.When the reason for this is explained with reference to FIG. 6, thetrack body 31 of the track rail 11 according to the first embodiment isformed by laminating a plurality of FRP reinforced fiber sheets S asshown in FIG. 6(a). Thus, as shown in FIG. 6(b), in the track rail 11according to the first embodiment, FRP has characteristics that canexert a large strength when a force applies in the direction of thereference sign a which is the direction orthogonal to the laminationdirection of the FRP reinforced fiber sheets S, but can exert only asmall strength when a force applies in the direction of the referencesign β which is the direction parallel to the lamination direction ofthe FRP reinforced fiber sheets S. That is, if the end housings 51 and52 are mounted by boring a screw hole or inserting a helisert in thedirection of the symbol β which is the direction parallel to thelamination direction of the FRP reinforced fiber sheets S forming thetrack rail 11, there is a difficulty in ensuring the strength.

In consideration of the above, the inventors have conceived a newstructure shown in FIG. 7. That is, a stepped machining portion 71 isformed at the end portion of the track body 31 formed of FRP, and amounting part 75 formed of a metal material is formed so as to be fittedto the portion where the stepped machining portion 71 is formed. Themounting part 75 is a member in which mounting holes 76 for mountingexternal members such as the end housings 51 and 52 are formed, and thewhole of the mounting part 75 is formed of a metal material.Furthermore, since the stepped machining portion 71 is formed in a shapealong the contour shape of the mounting part 75, when the mounting part75 is fitted to the stepped machining portion 71, the outer shape of thetrack rail 11 as an elongated member is formed in a smooth contour shapehaving an even outer dimension.

Moreover, at the portion of the mounting part 75 and the steppedmachining portion 71 formed in the track body 31, joint holes 72, 73,77, and 78 opened in the direction orthogonal to the laminationdirection of the FRP reinforced fiber sheets S forming the track body 31(that is, in the direction of the reference sign a in FIG. 6(b)) at thetime of the joint are formed.

The joint holes 72, 73, 77, and 78 in the first embodiment are formed soas to be opened in the two directions. The joint holes 72 and 77 areopened in a first direction facing the bottom surface side of the trackrail 11 having the substantially U-shaped vertical section, and thejoint holes 73 and 78 are opened in a second direction facing the leftand right sides of the track rail 11 having the substantially U-shapedvertical section and orthogonal to the first direction. By using thejoint holes 72, 73, 77, and 78 which are opened in these two directions,the mounting part 75 can be jointed to the stepped machining portion 71formed in the track body 31. Note that, as jointing means placed in thejoint holes 72, 73, 77, and 78, either of a bolt or a rivet or acombination thereof is used for example, and the jointing means usingbolts 80 is exemplified in the first embodiment shown in FIG. 7.

In addition, the end portion of the bolt 80 reaches a member to bescrewed with, and the jointing force exerted by the male screw of thebolt 80 is thereby increased. For example, in the relation between thejoint holes 72 and 77 opened in the first direction and the bolt 80, bydesigning the joint hole 72 formed in the stepped machining portion 71to be larger than the bolt shaft diameter, and forming the female screwonly in the joint hole 77 formed in the mounting part 75, the jointingforce from the bolt 80 acts only on the mounting part 75, and the trackbody 31 in which the stepped machining portion 71 is formed can beformed so as to be held between the bolt 80 and the mounting part 75.Similarly, in the relation between the joint holes 73 and 78 opened inthe second direction and the bolt 80, by designing the joint hole 78formed in the mounting part 75 to be larger than the bolt shaftdiameter, and forming the female screw only in the joint hole 73 formedin the stepped machining portion 71, the jointing force from the bolt 80acts only on the stepped machining portion 71, and the mounting part 75can be formed so as to be held between the bolt 80 and the steppedmachining portion 71. With such a structure, since a play margin betweenthe mounting part 75 and the stepped machining portion 71 in themounting using the jointing means such as the bolts 80, it is possibleto easily adjust the mounting position.

Furthermore, since the joint holes 72, 73, 77, and 78 in the firstembodiment are opened in the direction orthogonal to the laminationdirection of the FRP reinforced fiber sheets S forming the track body 31(that is, the direction of the reference sign α in FIG. 6(b)), thejointing force exerted by the jointing means such as the bolts 80 actsin the direction orthogonal to the lamination direction of the FRPreinforced fiber sheet S. That is, since the track body 31 formed of FRPcan receive the strong jointing force exerted by the jointing means suchas the bolts 80, it is possible to achieve the stable joint with highaccuracy between the track body 31 formed of the FRP and the mountingpart 75 formed of a metal material.

Furthermore, when external members such as the end housings 51 and 52are mounted on the track rail 11 using the mounting hole 76 of themounting part 75 formed of a metal material, the mounting part 75 issecurely fixed to the track body 31 and the mounting hole 76 is formedof a metal material. Thus, the problem in the conventional techniquedescribed in the paragraphs of the background art is solved, and it ispossible to achieve the state in which external members are securelymounted on the track rail 11 according to the first embodiment with highaccuracy.

Moreover, since the mounting part 75 according to the first embodimentis formed of a metal material, it is possible to secure the right angleof the end face of the mounting part 75 by, for example, grinding theend face or the like after the joint to the track body 31. That is,although the accuracy of the outer dimension is not as high as that of ametal material in the case of the track rail formed of FRP alone, bycombining the track body 31 formed of FRP and the mounting part 75formed of a metal material to form the track rail 11 as in the firstembodiment, it is possible to provide the track rail 11 having higheraccuracy of the outer dimension.

The additional feature of the motion guide device 10 according to thefirst embodiment has been described with reference to FIGS. 5 to 7.Although the feature of the present invention described with referenceto FIGS. 5 to 7 is the case of the application to the track rail 11, thefeature is also applicable to the movable member 13, and a specificexample is shown in FIG. 8. Here, FIG. 8 is a view showing a case inwhich the first embodiment is applied to a movable member.

In the case of a movable member 83 exemplified in FIG. 8, the whole isformed of CFRP. The lids 18 to be placed on both end faces of themovable member 83 are formed of resin. At this time, if the lids 18 aresimply fastened to the movable member 83 with the bolts 80, the bolts 80are fastened and fixed in the direction parallel to the laminationdirection of the CFRP reinforced fiber sheets S, and a small fasteningforce can only be exerted due to the characteristics of the CFRP formingthe movable member 83. Thus, in the case of the embodiment shown in FIG.8, rectangular notches are formed in the vicinities of both end faces ofthe movable member 83 formed of CFRP, and fastening metal fittings 85formed of a metal material are inserted into the notches. A joint hole88 is formed in the fastening metal fitting 85 in the side facedirection at the time of the insertion into the movable member 83 (theobliquely downward direction to the right in FIG. 8), and the openingdirection of the joint hole 88 is orthogonal to the lamination directionof the CFRP reinforced fiber sheet S. By inserting a fastening knock pin80 a into the joint hole 88, it is possible to achieve the state inwhich the fastening metal fitting 85 is securely stably jointed to themovable member 83.

Furthermore, a mounting hole 86 for mounting the lid 18 is formed in theend face direction of the fastening metal fitting 85 (the obliquelydownward direction to the left in FIG. 8), and by using the mountinghole 86 and the bolt 80, it is possible to achieve the stable mountingof the resin lid 18 to the CFRP movable member 83.

Similarly to the case of the track rail 11 in the first embodiment,since the fastening metal fittings 85 exemplified in FIG. 8 are alsoformed of a metal material, it is possible to secure the right angle ofthe end face by grinding the end face or the like after the joint to themovable member 83. That is, although the accuracy of the outer dimensionis not as high as that of a metal material in the case of a movablemember formed of CFRP alone, by combining and forming the movable member83 formed of CFRP and the fastening metal fitting 85 formed of a metalmaterial as in this embodiment, it is possible to provide the movablemember 83 having higher accuracy of the outer dimension.

With the motion guide device 10 according to the first embodimentdescribed above, it is possible to provide the motion guide device 10,which is formed of FRP, having the means for securely mounting anexternal member. According to the motion guide device 10, it is possibleto improve the mountability of an external member which is a difficultyin applying FRP, and to further achieve weight reduction while securingthe necessary strength which is an advantage of FRP. Note that, althougha nonferrous metal represented by aluminum or the like can achieveweight reduction, it has a difficulty in weak strength. That is, whilethe Young's modulus of iron is 206 GPa, the Young's modulus of aluminumis about 68 GPa. Thus, if a motion guide device is formed of anonferrous metal represented by aluminum or the like, although weightreduction can be achieved, it is difficult to secure the necessarystrength as high as that of an iron-based material.

In contrast, regarding FRP, it is possible to achieve a very highYoung's modulus, and it is possible to secure a Young's modulus of CFRPof about 50 to 400 GPa, for example. By using CFRP so as to receive aforce in the direction orthogonal to the lamination direction of theCFRP reinforced fiber sheets S as in the first embodiment, it ispossible for CFRP to exert strength close to the maximum Young's modulusof 400 GPa. That is, according to the motion guide device 10 to whichthe present invention is applied, it is possible to improve themountability of an external member which is a difficulty in applyingFRP, and to further achieve weight reduction while securing thenecessary strength which is an advantage of FRP.

In addition, since FRP is a material having an excellent dampingcharacteristic, it is possible to exert an advantageous effect whenapplied to the motion guide device 10. For example, in the case of usingthe motion guide device 10 in a cantilever manner, it is possible toobtain the effect of shortening the stop time until the vibration stops.That is, when the motion guide device 10 has to be installed in acantilever manner due to the restriction of a use environment, by thedamping characteristic of FRP, it is possible to quickly eliminatevibrations caused by external influence, and to achieve tact-up of thestationary state recovery cycle of the motion guide device 10.

The preferred embodiment of the present invention has been describedabove, but the technical scope of the present invention is not limitedto the scope described in the first embodiment. Various modifications orimprovements can be added to the first embodiment.

For example, in the track rail 11 according to the first embodimentshown in FIG. 7, the mounting part 75 formed of a metal material has asubstantially L-shaped outer shape, and the stepped machining portion 71for mounting the mounting part 75 is formed over the left and right sidesurfaces and the bottom surface of the track rail 11. However, it ispossible to arbitrarily change the shape of the stepped machiningportion according to the present invention and the shape of the mountingpart to be mounted to the stepped machining portion. For example, asshown in FIG. 9, by forming a stepped machining portion 91 only on theleft and right side surfaces of the track rail 11, and a mounting part95 having a shape along the shape of the stepped machining portion 91may be mounted by the bolt 80. In the case shown in FIG. 9, since thedirection in which the bolt 80 is jointed is the direction orthogonal tothe lamination direction of the FRP reinforced fiber sheets S formingthe track rail 11, it is possible to achieve the state in which themounting part 95 is securely jointed to the track rail 11. Note that,FIG. 9 is a view showing an example of various possible modifications ofthe motion guide device according to the first embodiment, and thedescriptions of the same members as or similar members to those in thefirst embodiment are omitted by assigning the same reference numerals.

Furthermore, for example, similarly to the track rail 11 according tothe first embodiment shown in FIG. 7, by forming the stepped machiningportion 71 over the left and right side surfaces and the bottom surfaceof the track rail 11, and a mounting part to be jointed to the steppedmachining portion 71 may be divided into two side mounting parts 95 aand one bottom mounting part 95 b. Such a case is shown in FIG. 10. FIG.10 is a view showing another example of various possible modificationsof the motion guide device according to the first embodiment, and thedescriptions of the same members as or similar members to those in thefirst embodiment are omitted by assigning the same reference numerals.In the case exemplified in FIG. 10, since the joint holes 72, 73, 77,and 78 are opened in the direction orthogonal to the laminationdirection of the FRP reinforced fiber sheets S forming the track body 31(that is, the direction of the reference sign α in FIG. 6(b)), thejointing force exerted by the jointing means such as the bolts 80 actsin the direction orthogonal to the lamination direction of the FRPreinforced fiber sheet S. That is, since the track body 31 formed of FRPcan receive the jointing force exerted by the jointing means such as thebolts 80 with strong force, it is possible to achieve the stable jointwith high accuracy between the track body 31 formed of the FRP and theside mounting part 95 a and the bottom mounting part 95 b which areformed of a metal material.

Second Embodiment

Next, as another possible embodiment of the present invention, a motionguide device 200 according to a second embodiment will be described withreference to FIG. 11. Here, FIG. 11 is a partial perspective viewshowing a main portion of a motion guide device according to the secondembodiment; FIG. 11(a) shows that a mounting part is not being mountedto a stepped machining portion, and FIG. 11(b) shows that the mountingpart is being mounted to the stepped machining portion. In FIG. 11, thedescriptions of the same members as or similar members to those in thefirst embodiment are omitted by assigning the same reference numerals.

In the motion guide device 200 according to the second embodiment,similarly to the case of the first embodiment, a stepped machiningportion 71 is formed at the end portion of a track body 31 formed ofFRP, and a mounting part 75 formed of a metal material is jointed so asto be fitted to the portion where the stepped machining portion 71 isformed. However, since an adhesive is used as jointing means in thesecond embodiment, a structure different from that in the firstembodiment is adopted. That is, in the second embodiment, a mountinghole for mounting an external member is not formed in the steppedmachining portion 71 formed at the end portion of the track body 31, andthe stepped machining portion 71 according to the second embodiment isformed as a joint surface extending in the direction parallel to thelamination direction of FRP reinforced fiber sheets forming the trackbody 31. Then, by applying an adhesive to the stepped machining portion71 which is the joint surface, and jointing the mounting part 75, atrack rail 211 of the motion guide device 200 according to the secondembodiment is manufactured.

In the second embodiment, mounting holes 76 for mounting externalmembers such as end housings 51 and 52 are also formed in the mountingpart 75, and the whole of the mounting part 75 is formed of a metalmaterial. Furthermore, since the stepped machining portion 71 is formedin a shape along the contour shape of the mounting part 75, when themounting part 75 is adhered to the stepped machining portion 71, theouter shape of the track rail 11 as an elongated member is formed in asmooth contour shape having an even outer dimension. Furthermore, in thesecond embodiment, the adhesive is used as the jointing means, which hasan advantage that it is easy to position the mounting part 75 withrespect to the stepped machining portion 71. That is, according to themotion guide device 200 according to the second embodiment, it ispossible to improve the mountability of an external member which is adifficulty in applying FRP, and to further achieve weight reductionwhile securing necessary strength which is an advantage of FRP.

Third Embodiment

In the motion guide devices 10 and 200 according to the first and secondembodiments described above, by forming the stepped machining portion 71at the end portion of the track body 31 formed of FRP, the mounting part75 formed of a metal material is jointed so as to be fitted to theportion where the stepped machining portion 71 is formed. However, thepresent invention is not applied only to the end portion of the trackbody 31, and can be applied to, for example, a plurality of boltmounting holes formed on the bottom surface side of the track rail 11having a substantially U-shaped vertical section at appropriateintervals in the longitudinal direction of the track rail 11. A specificexample will be described with reference to FIGS. 12 and 13. Here, FIG.12 is a view for explaining a motion guide device according to a thirdembodiment; FIG. 12(a) is a perspective view showing the overallstructure of the motion guide device, FIG. 12(b) is a vertical sectionalview of a main portion showing the vicinity of a bolt mounting hole, andFIG. 12(c) is a schematic view for explaining the characteristics of FRPthat is a constituting member of a track rail. In addition, FIG. 13 is aview showing a specific implementation example of the third embodiment.

As shown in FIG. 12, in a motion guide device 300 according to the thirdembodiment, a plurality of bolt mounting holes 311 b are formed on thebottom surface side of a track rail 311 having a substantially U-shapedvertical section and at appropriate intervals in the longitudinaldirection of the track rail 311. Then, as shown in FIG. 12(b), in thebolt mounting hole 311 b according to the third embodiment, the diameterof the hole is changed at the center portion of the bolt mounting hole311 b opened in the vertical direction. In other words, the hole on theupper side of the track rail 311 is formed to have a large openingdiameter, while the hole on the lower side of the track rail 311 isformed to have a small opening diameter. That is, in the bolt mountinghole 311 b according to the third embodiment, the stepped machiningportion according to the present invention is formed. Furthermore, asshown in FIG. 12(c), since the bolt mounting hole 311 b having thestepped machining portion is opened in the direction orthogonal to thelamination direction of FRP reinforced fiber sheets S forming the trackbody 331 (that is, the direction of the reference sign a in FIG. 6(b)),the structure in which FRP can exhibit a large strength is adopted.

A metal collar 375 having a flange portion on the upper side isadhesive-jointed with an adhesive to the bolt mounting hole 311 b havingthe stepped machining portion. This metal collar 375 is a member formedof a metal material in which a mounting hole 376 for mounting anexternal member is formed, and functions as the mounting part accordingto the present invention.

By fixing the track rail 311 to the bolt mounting hole 311 b and themetal collar 375 according to the third embodiment formed as describedabove with the bolt 80 as shown in FIG. 13, it is possible to providethe motion guide device 300 that achieves a fixation state as strong asthe case of using an iron-based material while FRP that is aweight-reduction material is used. When the bolt 80 is inserted into themetal collar 375 for fastening, it is preferable to use a metallicwasher 81 inserted between the upper part of the metal collar 375 andthe head part of the bolt 80. At this time, since the bolt mounting hole311 b and the metal collar 375 are strongly jointed and fixed with theadhesive, the metal collar 375 does not corotate due to the rotationalforce at the time of fastening the bolt 80, and this does not damage theFRP forming the track body 331. Thus, according to the third embodiment,it is possible to provide the motion guide device 300 in which a strongbolt fastening force to the track rail 311 can be stably exerted.

Note that, an improvement as shown in FIG. 14 can be applied to themetal collar 375 according to the third embodiment. Here, FIG. 14 is apartial vertical sectional view showing an example an improvement of themetal collar according to the third embodiment. That is, by tapping theinner peripheral surface of the mounting hole 376 of the metal collar375 according to the third embodiment to form a screw groove and usingthe screw groove, the track rail 311 may be mounted. This structure ispreferable because the fastening force from the bolt 80 acts morestrongly on the metal collar 375 formed of a metal material.

Fourth Embodiment

In the third embodiment described above, it has been described that thepresent invention is applied to the bolt mounting holes 311 b formed onthe bottom surface side of the track rail 311 having a substantiallyU-shaped vertical section at appropriate intervals in the longitudinaldirection of the track rail 311. Further modifications can be applied tothe third embodiment. With reference to FIGS. 15 and 16, a motion guidedevice according to a fourth embodiment will be described. Here, FIG. 15is a view for explaining a track rail used in the motion guide deviceaccording to the fourth embodiment; FIG. 15(a) is an explodedperspective view showing the bottom surface side of the track railbefore assembly, FIG. 15(b) is a perspective view showing the bottomsurface side of the track rail after assembly, and FIG. 15(c) is aperspective view showing the upper surface side of the track rail afterassembly. In addition, FIG. 16 is a view showing a case in which a boltas fastening means is placed to a state view showing a section A-A inFIG. 15(c).

A track rail 411 used in the motion guide device according to the fourthembodiment has a groove-shaped portion 471, which has a substantiallyoblong shape, formed on the bottom surface side of the track rail 411having a substantially U-shaped vertical section, and on the bottomsurface side of each portion where a plurality of bolt mounting holes411 b is formed at appropriate intervals in the longitudinal directionof the track rail 411. The groove-shaped portion 471 is a portion havinga function as the stepped machining portion according to the presentinvention. A reinforcing mounting part 475 formed of a metal materialshown in FIG. 15(a) is fitted into the groove-shaped portion 471 as thestepped machining portion. A large-diameter joint hole 477 is formed inthe center portion of the reinforcing mounting part 475, and twosmall-diameter joint holes 478 are formed on both sides of thelarge-diameter joint hole 477. When the reinforcing mounting part 475 isfitted into the groove-shaped portion 471 as the stepped machiningportion, the bolt mounting hole 411 b formed in the track rail 411 andthe large-diameter joint hole 477 overlap each other, and a holeconducts. Bolt holes 411 c are formed in front and rear of the portionwhere the bolt mounting hole 411 b is formed in the track rail 411. Whenthe reinforcing mounting part 475 is fitted into the groove-shapedportion 471 as the stepped machining portion, the small-diameter jointholes 478 and the bolt holes 411 c overlap each other, and holesconduct. Thus, by fastening the bolts 80 to the small-diameter jointholes 478 using the bolt holes 411 c formed in the front and the rear ofthe position where the bolt mounting hole 411 b is formed in the trackrail 411, it is possible to strongly fix the reinforcing mounting part475 to the track body 431 (see FIGS. 15(b), 15(c) and 16).

Furthermore, as shown in FIG. 16, by inserting the bolt 80 to the jointhole 477 and the bolt mounting hole 411 b for fastening using thelarge-diameter joint hole 477 formed in the reinforcing mounting part475 and the bolt mounting hole 411 b formed in the track rail 411, it ispossible to strongly fix the track rail 411 to an object to be fixed. Inthe fourth embodiment, since the fixing force to the object to be fixedmainly acts on the reinforcing mounting part 475, and the fixing forcedoes not substantially reach the track body 431 formed of FRP, it ispossible to suitably prevent the track rail 411 from distortion or shapedeformation due to the fastening force of the bolt 80, and to achievethe state in which the motion guide device is stably mounted.

The preferred embodiments of the present invention have been describedabove, but the technical scope of the present invention is not limitedto the scope described in the above embodiments. Various modificationsor improvements can be added to the above embodiments.

For example, in the first to fourth embodiments, it has been describedthat the present invention is applied to the motion guide device havingan integral structure in which a linear motion guide and a ball screware combined. However, the present invention is applicable to any motionguide devices such as general rolling bearings used for machine tools,non-lubricant bearings used in vacuum, linear guides, linear guidedevices, ball spline devices, ball screw devices, and roller rings.

In the motion guide device according to the first to fourth embodiments,it has been exemplified that the balls 12 as the rolling bodies areconfigured so as to circulate in the infinite circulation passage 20 ininfinitum, but the rolling bodies may be configured as a roller, and therolling bodies are not limited to the infinite circulation type, and maybe a finite circulation type.

Furthermore, in the motion guide device according to the first to fourthembodiments, it has been exemplified that the track rail 11 as the trackmember and the movable member 13 are placed via the balls 12 as therolling bodies. However, the present invention is applicable not only tosuch a device with a rolling guide motion but also to a motion guidedevice with a sliding motion in which a track member and a movablemember are placed without rolling bodies such as balls or rollers.

Moreover, the FRP used in the motion guide device according to the firstto fourth embodiments is a material the strength of which is improved byadding reinforced fiber such as glass fiber to synthetic resin, but themolding method of FRP is not limited in the application to the presentinvention. That is, FRP, to which the present invention is applicable,manufactured by any molding method, such as a hand lay up method inwhich reinforced fiber are laid in a mold and a resin mixed with acuring agent is repeatedly laminated while defoaming, a spray up method,or a sheet molding compounds (SMC) press method in which a sheet mixtureof reinforced fiber and resin is compressed and molded with a metalmold, can be used.

Note that, the motion guide device according to each embodiment can beconfigured as a ball screw device as shown in FIG. 17, for example.Here, FIG. 17 is a view exemplifying a case in which the motion guidedevice according to the present invention is configured as a ball screwdevice. In other words, the motion guide device according to the presentinvention can be configured as a ball screw device 510 having a screwshaft 511 as a track member and a nut 513 as a movable member mounted tothe screw shaft 511 so as to be relatively rotatable via a plurality ofballs 512, the vicinity of a rolling body rolling surface where thescrew shaft 511 or the nut 513 contacts with the balls 512 can be formedof a metal material, and the other portion can be formed of FRP. Theball screw device can also be configured so that a mounting part and atrack body or a movable body each have a joint hole opened in thedirection orthogonal to the lamination direction of FRP reinforced fibersheets forming the track body or the movable body at the time of thejoint, and can be jointed using jointing means placed in the jointholes. By configuring the ball screw device 510 in this manner, it ispossible to provide a motion guide device that achieves a state in whichan external member is securely mounted with high accuracy and weightreduction of the device.

It is obvious from the description of claims that such modifications orimprovements can be included in the technical scope of the presentinvention.

REFERENCE NUMERALS 10, 200, 300: motion guide device, 11, 211, 311, 411:track rail, 11 a: rolling-body rolling groove, 11 b, 311 b, 411 b: boltmounting hole, 12: ball, 13, 83: movable member, 13 a:loaded-rolling-body rolling groove, 13 b: opening, 13 c: upper surface,13 d: female screw, 14: screw shaft, 15: loaded-rolling-body rollingpassage, 16: return passage, 17: direction change passage, 18: lid, 19:non-loaded-rolling-body rolling passage, 20: infinite circulationpassage, 21: spacer member, 30, 40, 41, 42, 44: rolling part, 31, 331,431: track body, 43: movable body, 51, 52: end housing, 71, 91: steppedmachining portion, 72, 73, 77, 78, 88, 477, 478: joint hole, 75, 95:mounting part, 76, 86: mounting hole, 80: bolt, 80a: fastening knockpin, 81: washer, 85: fastening metal fitting, 95 a: side mounting part,95 b: bottom mounting part, 375: metal collar, 376: mounting hole, 411c: bolt hole, 471: groove-shaped portion, 475: reinforcing mountingpart, 510: ball screw device, 511: screw shaft, 512: ball, 513: nut, S:reinforced fiber sheet

1. A motion guide device comprising: a track member; and a movablemember mounted on the track member so as to freely move via a pluralityof rolling bodies, wherein the track member or the movable membercomprises: a rolling part formed of a metal material contacting with theplurality of rolling bodies and forming a rolling body rolling surface;a mounting part formed of a metal material having a mounting hole formounting an external member; and a track body or a movable body formedof FRP jointed with the rolling part and the mounting part and formingthe track member or the movable member, and the mounting part and thetrack body or the movable body each have a joint hole opened in adirection orthogonal to a lamination direction of FRP reinforced fibersheets forming the track body or the movable body at a time of thejoint, and can be jointed using jointing means placed in the jointholes.
 2. A motion guide device comprising: a track member; and amovable member mounted on the track member so as to freely move via aplurality of rolling bodies, wherein the track member or the movablemember comprises: a rolling part formed of a metal material contactingwith the plurality of rolling bodies and forming a rolling body rollingsurface; a mounting part formed of a metal material having a mountinghole for mounting an external member; and a track body or a movable bodyformed of FRP jointed with the rolling part and the mounting part andforming the track member or the movable member, and the mounting partand the track body or the movable body each have a joint surfaceextending in a direction parallel to a lamination direction of FRPreinforced fiber sheets forming the track body or the movable body at atime of the joint, and can be jointed using jointing means applied tothe joint surfaces.
 3. The motion guide device according to claim 1,wherein the track body or the movable body has a stepped machiningportion formed along a shape of the mounting part at a portion where themounting part is to be jointed.
 4. The motion guide device according toclaim 1, wherein the jointing means is any one of or a combination of abolt, a rivet, and an adhesive.
 5. The motion guide device according toclaim 1, wherein the track member is formed as a member having asubstantially U-shaped section, and a plurality of the joint holes isformed so as to be opened in, at least, two directions of a firstdirection facing a bottom surface side of the substantially U-shapedsection, and a second direction facing a left and right surface sides ofthe substantially U-shaped section and orthogonal to the firstdirection.
 6. An actuator incorporating the motion guide deviceaccording to claim 1.